500 LAUREL DR 2016-01-01 MF Import

Geotechnical Engineering Study 00-2267 Three Story Addition - 500 Laurel Street, Everett January 31, 2001 Page 32 T Short Term Drainage Measures: Over the shoR term, we recorr;nend that the eaRhwork contractor be prepared to instail several shallow sump pits to collect water in foundation or utility excavations. All collected water should be pumped to a positive and permanent discharge. (A positive and permanent discharge might consist of a nearhy storm drain catch basin.) It is essential that all surface runoff be directed away from the crest line of all excavations, including utility trenches, or from the westera bluff slope, and not be allowed to sheet Oow over the exposed surfaces. Thus the site s��rface adjacent to a trench or slope crestline should be graded so that surface water is directed �way from that feature a�d off the site (in this case roughly towards the northeast). Water should not be allowed to stand in any area where a builriing, floor slab, or pavement is to be constructed. During construction, the earthwork contractor should roller seal all louse surfaces at night or at the beginning of a weekend to reduce the potential for moisture infiltration into the subgrade soils. Site grades should allow for drainage away from building foundations. We suggest that the ground be sloped at a gradient of thre� percent for a distance of at least ten (10) feet away from a building, except in areas that are to be paved. Ifwork is to cease at a weekend and the subgrades remain exposed to the elements we recommend tha# the construction area be covered with an impervious membrana, such as a tarpaulin. Any excavation or slope areas, including utility trench excavations, should be protected against the elements during construction. This can generaily bA accomplished by overlaying the exposed slope surface with a sandbagged or pegged-in-place visqueen barrier. Temporary site grading should be performed to create site grades that direct water away from the excavation. We also recommend that the contractor consider installing either a shallow swale or ditch along the toe of any protected slope to collect any surface water runoff and to direct it to a positive and permanent discharge. Long Term Drainage Measures: In the long term, perhaps the most critical element of drainage control is to install footing drains around tne perimeters of the building foundation. These drains should consist o# a perforated, rigid, smooth- walled, plastic pipe bedded on and surrounded by a free-drain�ng granular material. The drain pipe, which should have a minimum diameter of four inches, should be placed at, or just below, the invert elevation of the foundation with the perforations � T I T r � � �1 i � � I